hrtimer: Rework hrtimer_nanosleep to make sys_compat_nanosleep easier

Pull the copy_to_user out of hrtimer_nanosleep and into the callers
(common_nsleep, sys_nanosleep) in preparation for converting
compat_sys_nanosleep to use hrtimers.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 31 insertions, 17 deletions

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 540799bc85f8..7a9398e19704 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -300,7 +300,7 @@ hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 
 /* Precise sleep: */
 extern long hrtimer_nanosleep(struct timespec *rqtp,
-                              struct timespec __user *rmtp,
+                              struct timespec *rmtp,
                               const enum hrtimer_mode mode,
                               const clockid_t clockid);
 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index dc8a4451d79b..b2b2c2b0a49b 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1286,8 +1286,7 @@ static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mod
 long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
 {
         struct hrtimer_sleeper t;
-        struct timespec __user *rmtp;
-        struct timespec tu;
+        struct timespec *rmtp;
         ktime_t time;
 
         restart->fn = do_no_restart_syscall;
@@ -1298,14 +1297,12 @@ long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
         if (do_nanosleep(&t, HRTIMER_MODE_ABS))
                 return 0;
 
-        rmtp = (struct timespec __user *) restart->arg1;
+        rmtp = (struct timespec *)restart->arg1;
         if (rmtp) {
                 time = ktime_sub(t.timer.expires, t.timer.base->get_time());
                 if (time.tv64 <= 0)
                         return 0;
-                tu = ktime_to_timespec(time);
-                if (copy_to_user(rmtp, &tu, sizeof(tu)))
-                        return -EFAULT;
+                *rmtp = ktime_to_timespec(time);
         }
 
         restart->fn = hrtimer_nanosleep_restart;
@@ -1314,12 +1311,11 @@ long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
         return -ERESTART_RESTARTBLOCK;
 }
 
-long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
+long hrtimer_nanosleep(struct timespec *rqtp, struct timespec *rmtp,
                        const enum hrtimer_mode mode, const clockid_t clockid)
 {
         struct restart_block *restart;
         struct hrtimer_sleeper t;
-        struct timespec tu;
         ktime_t rem;
 
         hrtimer_init(&t.timer, clockid, mode);
@@ -1335,9 +1331,7 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
                 rem = ktime_sub(t.timer.expires, t.timer.base->get_time());
                 if (rem.tv64 <= 0)
                         return 0;
-                tu = ktime_to_timespec(rem);
-                if (copy_to_user(rmtp, &tu, sizeof(tu)))
-                        return -EFAULT;
+                *rmtp = ktime_to_timespec(rem);
         }
 
         restart = &current_thread_info()->restart_block;
@@ -1353,7 +1347,8 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
 asmlinkage long
 sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
 {
-        struct timespec tu;
+        struct timespec tu, rmt;
+        int ret;
 
         if (copy_from_user(&tu, rqtp, sizeof(tu)))
                 return -EFAULT;
@@ -1361,7 +1356,15 @@ sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
         if (!timespec_valid(&tu))
                 return -EINVAL;
 
-        return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+        ret = hrtimer_nanosleep(&tu, rmtp ? &rmt : NULL, HRTIMER_MODE_REL,
+                                CLOCK_MONOTONIC);
+
+        if (ret && rmtp) {
+                if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
+                        return -EFAULT;
+        }
+
+        return ret;
 }
 
 /*
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index d71ed09fe1dd..d11f579d189a 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -981,9 +981,20 @@ sys_clock_getres(const clockid_t which_clock, struct timespec __user *tp)
 static int common_nsleep(const clockid_t which_clock, int flags,
                          struct timespec *tsave, struct timespec __user *rmtp)
 {
-        return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
-                                 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
-                                 which_clock);
+        struct timespec rmt;
+        int ret;
+
+        ret = hrtimer_nanosleep(tsave, rmtp ? &rmt : NULL,
+                                flags & TIMER_ABSTIME ?
+                                HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
+                                which_clock);
+
+        if (ret && rmtp) {
+                if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
+                        return -EFAULT;
+        }
+
+        return ret;
 }
 
 asmlinkage long